The technology of fiber optics is constantly changing. These technologies proliferate many technological areas including communications systems, sensors semiconductors, and laser technologies. Newly emerging areas employ fiber optics in a variety of ways. For example, fiber light amplifiers for fiber optic communications, fiber lasers for CD ROM applications, nonlinear fibers for optical switches, and fiber stress sensors in structure represent just a few of the applications of fiber optics.
Related art describes the fabrication of fibers which consist of a glass core covered with a glass tube to form the cladding that acts as a shield. The core serves to guide the light. Related art also describes coating the glass core with a film which is interposed between the glass core and the glass tube. The coatings used to produce the films can include various inorganic materials such as semiconductors, metals, alloys, magnetic materials, ferrites and ceramics. These films can be employed for a variety of purposes, considering the fact that properties of light traveling in the core can be modified by the presence of a specific coating. The related prior art however, fails to teach exactly how these fibers are to be fabricated when employing a wide variety of coating materials.
The fabrication of the fibers begins with the manufacture of a "preform". The "preform" is constructed by placing a micrometer or less coating on a glass rod which eventually becomes the core of the optical fiber. The coated rod is then placed inside of a larger diameter glass tube. In one case the glass tube is then sealed at one end in a vacuum in the space between the coated rod and the tube. This assembly is then heated which causes the glass of the outer tube to collapse onto the coated rod. Additional glass tubes are collapsed on to this structure until the desired outside diameter of the preform is reached. This assembly is the "preform". Once the "preform" is constructed, it is then heated to a softening temperature of the glass, and fibers are drawn from the "preform". However, since the films are relatively thin, typically 10 nanometers or less, difficulty often arises when the fibers are drawn from the "preform" as the films tend to fracture and loose their continuity. The related prior art does not teach a reliable method of fabricating fibers which ensures that the continuity of the film layer is maintained as the fibers are drawn from the "preform". That is, the resulting film material only covers portions of the fiber due to breaks in the material. Moreover, the related art also fails to discuss a method for ensuring that the film layer will remain coherent and homogeneous during the drawning step.
In view of the above, there is a need in the art for a method of fabrication which ensures that the film layer maintains coherency, continuity and homogeneity as fibers are drawn from the "preform".